Rotary Driven Pipe Piles for a 14-Story Building in New York City

Rotary driven pipe piles are a unique solution for foundation construction in constrained urban areas. These piles consist of a closedend, steel casing with sacrificial drill tip. The casing and drill tip are rotated into the ground using a fixed-mast drill rig. Three hundred sixty two 12.75-inch diameter, rotary driven pipe piles were installed to support a 14-story building in the upper east side of Manhattan. The soils consisted of uncontrolled fill, organic silts, and peat over stiff, saturated, varved silts and clays. A novel mathematical relationship between capacity, installation crowd, and torque was used to develop initial pile installation criteria. A simple discrete element model showed the piles would exhibited considerable freeze. This was verified by successive torque readings over time. Four compression, one tension, and one lateral load test were performed. Torque measurements, load test results, and installation observations are presented. All piles performed exceptionally well during the test program in terms of total pile head deflection. Overall, field measurements matched predictions. Careful coordination and communication between all parties allowed pile installation to proceed rapidly; the foundation was completed on schedule and budget. Each pile was fitted with a geothermal conduit loop to create ‘energy piles’, which will be instrumented for future case study research

REVIEW OF MARTIAN DUST COMPOSITION, TRANSPORT, DEPOSITION, ADHESION, AND REMOVAL

Abstract Adverse effects of dust accumulation on spacecraft and rover surfaces hinder the functioning of equipment on Mars and consequently limit mission duration. Hence, dust is an important parameter in the design, development, and testing of equipment for Mars surface missions. A review of Martian dust composition, transport, deposition, adhesion, and removal is presented. Martian dust has consistent average chemical and mineralogical composition over the entire planet. Sources of dust transport and deposition on the surface of Mars include ordinary atmospheric settling, dust storms, dust devils, near surface saltation, and artificial human/robotic disturbance of the regolith. Mechanisms of dust adhesion include chemical bonding, cementation, ice bridges, capillary forces, van der Waals forces, and electrostatic forces. There are a number of different methods to cause particle removal including vibration, centrifuge, impact, electrostatic repulsion, liquid or air flow, thermophoresis, and direct manipulation using a mechanical device. This paper presents a summary of what is known about Martian dust and its removal to date